<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            font-size: 20px;
        }
        .warp{
            width: 10vw;
            height: 10em;
            background-color: #f50909;
        }

    </style>
</head>
<body>
    <div class="box">
        <div class="warp">hello </div>
    </div>
</body>
</html>